Why one is quite enough

THIS WEEK the Human Fertilisation and Embryology Authority (HFEA) said that we needed to reduce the number of hazardous multiple births caused by IVF.

Only 1 or 2 in every 100 natural conceptions results in twins; with IVF, the figure is 23 in every 100. The HFEA estimates that the deaths of 126 IVF twins could have been avoided had they been born singly. It is now consulting on the issue.

Multiple embryo transfer has always been justified on the ground that it maximises the chances of pregnancy. But research in 2004, involving 660 women in Scandinavian countries, began what was to become a torrent of evidence demonstrating that using one good-quality embryo can be as successful in assuring pregnancy as using two.